ROLES OF FUNGI AND BACTERIA IN THE MINERALIZATION OF THE PESTICIDES ATRAZINE, ALACHLOR, MALATHION AND CARBOFURAN IN SOIL

Different roles for fungi and bacteria in the biotransformation pathways of pesticides in the soil were demonstrated. The pesticides studied were malathion (diethyl mercaptosuccinate S-ester 0,0 dimethyl phosphorodithioate), alachlor (2-chloro-N-[2-6-diethylphenyl]-N-[methoxy methyl] acetamide), atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine-2,4 diamine) and carbofuran (2,3-dihy-dro-2,2-dimethyl-7-benzofuranyl methylcarbamate). The mineralization of alkyl-side chains of alachlor and alkyl-amino-side chains of atrazine was found to be mainly due to fungal activity. Neither heterocyclic ring-labelled atrazine nor aromatic ring-labelled alachlor were degraded when fungi or bacteria were separately inhibited. The mineralization of carbofuran and malathion was mainly due to bacterial activity. These results indicate that the biodegradation of pesticides in the soil is performed by both fungi and bacteria. The mechanism of this phenomenon and the mode of action of the two microbial groups are discussed.